First steps towards a target laboratory at GANIL

The development of large-isotopically enriched 208Pb and 209Bi targets and the production of thin carbon films are described. Their use on rotating wheels in heavy-ion fusion reactions with intense 58Fe, 76Ge and 48Ca beams is reported

Potent single-domain antibodies that arrest respiratory syncytial virus fusion protein in its prefusion state

Human respiratory syncytial virus (RSV) is the main cause of lower respiratory tract infections in young children. The RSV fusion protein (F) is highly conserved and is the only viral membrane protein that is essential for infection. The prefusion conformation of RSV F is considered the most relevant target for antiviral strategies because it is the fusion-competent form of the protein and the primary target of neutralizing activity present in human serum. Here, we describe two llama-derived single-domain antibodies (VHHs) that have potent RSV-neutralizing activity and bind selectively to prefusion RSV F with picomolar affinity. Crystal structures of these VHHs in complex with prefusion F show that they recognize a conserved cavity formed by two F protomers. In addition, the VHHs prevent RSV replication and lung infiltration of inflammatory monocytes and T cells in RSV-challenged mice. These prefusion F-specific VHHs represent promising antiviral agents against RSV

Direct mass measurements of 19B, 22C, 29F, 31Ne, 34Na and other light exotic nuclei

We report on direct time-of-flight based mass measurements of 16 light neutron-rich nuclei. These include the first determination of the masses of the Borromean drip-line nuclei $^{19}$B, $^{22}$C and $^{29}$F as well as that of $^{34}$Na. In addition, the most precise determinations to date for $^{23}$N and $^{31}$Ne are reported. Coupled with recent interaction cross-section measurements, the present results support the occurrence of a two-neutron halo in $^{22}$C, with a dominant $\nu2s_{1/2}^2$ configuration, and a single-neutron halo in $^{31}$Ne with the valence neutron occupying predominantly the 2$p_{3/2}$ orbital. Despite a very low two-neutron separation energy the development of a halo in $^{19}$B is hindered by the 1$d_{5/2}^2$ character of the valence neutrons.Comment: 5 page

A retrospective description of primary immuno­deficiency diseases at Red Cross War Memorial Children’s Hospital, Cape Town, South Africa, 1975 - 2017

Background. The primary immunodeficiency diseases (PIDs) constitute a diverse and ever-expanding group of inborn errors affecting a wide range of immune functions. They are not well documented in sub-Saharan Africa.Objectives. To describe the spectrum of PIDs at a tertiary paediatric hospital.Methods. A retrospective descriptive study of PIDs diagnosed at Red Cross War Memorial Children’s Hospital, Cape Town, South Africa (SA), between 1975 and 2017 was undertaken.Results. We identified 252 children with PIDs, spanning eight of the nine categories listed in the 2017 classification of the International Union of Immunological Societies. Predominantly antibody deficiencies, combined immunodeficiencies with associated syndromic features, and immunodeficiencies affecting cellular and humoral immunity accounted for most children with PIDs (n=199, 79.0%). The mean age (standard deviation) at diagnosis was 46 (50) months, and the male/female ratio was 1.5:1. There was a history of parental consanguinity in 3 cases (1.2%). Recurrent infection was the most prevalent presenting phenotype, manifesting in 177 patients (70.2%). Genetic or chromosomal confirmation was obtained in 42/252 cases (16.7%). Common interventions used to prevent infection were antimicrobial prophylaxis and immunoglobulin replacement therapy, administered to 95 (37.7%) and 93 (36.9%) of the patients, respectively. Six of 7 children who underwent haematopoietic stem cell transplantation (HSCT) had successful outcomes. The 7th patient died 2 months after HSCT from overwhelming infection. Although we could not account for the children lost to follow-up during the study period, 53 deaths were confirmed (21.0%).Conclusions. Several challenges exist in the recognition and treatment of children with PIDs in our setting. These include limited access to genetic diagnostics and HSCT. Suboptimal treatment options contribute to the overall mortality of PIDs in SA.

Focal Plane Detector System of SHARAQ Spectrometer

International audienceThis report describes the basic performance of the detector system installed in the final momentum-dispersive focal plane of the SHARAQ spectrometer

Performance of the improved larger acceptance spectrometer: VAMOS++

International audienceMeasurements and ion optic calculations showed that the large momentum acceptance of the VAMOS spectrometer at GANIL could be further increased from $\sim$ 11% to $\sim$ 30% by suitably enlarging the dimensions of the detectors used at the focal plane. Such a new detection system built for the focal plane of VAMOS is described. It consists of larger area detectors (1000 mm × 150 mm) namely, a Multi-Wire Parallel Plate Avalanche Counter (MWPPAC), two drift chambers, a segmented ionization chamber and an array of Si detectors. Compared to the earlier existing system (VAMOS), we show that the new system (VAMOS++) has a dispersion-independent momentum acceptance . Additionally a start detector (MWPPAC) has been introduced near the target to further improve the mass resolution to $\sim$ 1/220. The performance of the VAMOS++ spectrometer is demonstrated using measurements of residues formed in the collisions of 129Xe at 967 MeV on 197Au

High precision position measurements at high counting rates with drift chambers and multi-hit electronics

11 pages, 7 figure

MAYA: An active-target detector for binary reactions with exotic beams

International audienceWith recent improvements in the production of radioactive beams in facilities such as SPIRAL at GANIL, a larger area of the nuclear chart is now accessible for experimentation. For these usually low-intensity and low-energy secondary beams, we have developed the new MAYA detector based on the active-target concept. This device allows to use a relatively thick target without loss of resolution by using the detection gas as target material. Dedicated 3D tracking, particle identification, energy loss and range measurements allow complete kinematic reconstruction of reactions taking place inside MAYA

Mass Measurements near N=Z

Abstract After an outline of the physics motivations, that illustrate why we think it is important to measure masses in the region N≈Z, we report on on experiments performed at Ganil. An experiment aimed at measuring the masses of proton-rich nuclei in the mass region A ≈ 60–80 has been performed, using a direct time-of-flight technique in conjunction with SISSI and the SPEG spectrometer at GANIL. The nuclei were produced via the fragmentation of a 78 Kr beam (73 meV/nucleon). A novel technique for the purification of the secondary beams, based on the stripping of the ions and using the α and the SPEG spectrometers, was succesfully checked. It allows for good selectivity without altering the beam quality. Secondary ions of 100 Ag, 100 Cd, 100 In and 100 Sn were produced via the fusion-evaporation reaction 50 Cr + 58 Ni at an energy of 5.1 MeV/nucleon, and were accelerated simultaneously in the second cyclotron of GANIL (CSS2). About 10 counts were observed from the production and acceleration of 100 Sn 22+ . The masses of 100 Cd, 100 In and 100 Sn were measured with respect to 100 Ag using the CSS2 cyclotron, with precisions of 2 × 10 −6 , 3 × 10 −6 and 10 −5 respectively